It is well known that certain surfaces of components included within an electrophotographic machine are susceptible to contamination by airborne contaminants. These airborne contaminants, including airborne particulates, fibers, aerosols, or chemical compounds, are typically generated as a result of operating the machine. Contamination tends to gradually accumulate on such surfaces so that periodic cleanings are necessary, even when concentrations of contaminants in the ambient air are low. The present invention relates to providing simple and economical means for cleaning certain surfaces that are adjacent to rollers utilized for forming toner images on receiver members.
In an electrophotographic machine a toner image is typically formed on an imaging member, transferred in a first transfer operation from the imaging member to an intermediate transfer member, and subsequently transferred in a second transfer operation from the intermediate transfer member to a receiver member (e.g., paper), whereupon the toner image is fixed to the receiver in a fusing station.
For full color high quality electrophotographic printing, it is known to employ a modular machine typically including four modules arranged in tandem fashion. Each module produces a respective single color toner separation image, e.g., a cyan, magenta, yellow, or black toner image. A receiver member is moved successively through the modules such that the respective single color toner images are sequentially transferred in registry to the receiver member. The receiver member, e.g., a paper sheet, can be electrostatically adhered to a transport belt, which transports the receiver member through the modules. After passing through the last module, the receiver member is moved through a fusing station where the unfused toner is fixed to the receiver member by heat and/or pressure. Each module can include a primary imaging roller (imaging cylinder) and a compliant intermediate transfer member (blanket cylinder). Arranged around the imaging cylinder in the direction of rotation are typically a charging station which can utilize a gridded corona charger, an exposure station for image-wise exposing the charged imaging cylinder so as to produce an electrostatic latent image, a development station for toning the latent image so as to produce a respective single color toner image, a primary transfer station wherein the respective single color toner image is electrostatically transferred to the blanket cylinder, and a cleaning station for cleaning the imaging cylinder prior to the next charging operation. A pre-clean corona charger may be mounted between the primary transfer station and the cleaning station, and additionally a pre-clean erase lamp may be mounted between the pre-clean corona charger and the cleaning station. The cleaning station can include a cleaning blade, a brush, or a rotatable member for contacting the surface of the imaging cylinder so as to remove residual untransferred toner particles therefrom. It is known to mount a sensor included in a densitometer immediately after the development station, which densitometer is used for monitoring toner coverage in a test patch located outside of the imaging area on the imaging cylinder. In the primary transfer station, the imaging cylinder forms a primary transfer nip with the blanket cylinder, and in a secondary transfer station, the blanket cylinder forms a secondary transfer nip for transferring the respective toner image to a receiver member, e.g., with the receiver member adhered to a transport belt such that the secondary transfer nip is formed by action of the blanket cylinder and an associated transfer roller or backup roller located behind the transport belt. A cleaning mechanism for the blanker cylinder is typically located after the secondary transfer station.
In an electrophotographic machine, image-wise exposure of an imaging cylinder can be done using a rastered laser beam and an associated polygon, as is well known. Periodic cleaning of such a polygon is typically required. It is possible to reliably clean the polygon inside the machine, e.g., by using an air jet or a cleaning roller, as disclosed for example in the Koguchi patent (U.S. Pat. No. 6,327,067). However, this requires a complicated apparatus. Alternatively, a LED writer including an array of lenses can be used for image-wise exposure, as disclosed for example in the Flynn, et al. patent (U.S. Pat. No. 4,947,195). It is noteworthy that such a LED writer is inherently much more amenable to cleaning than is the polygon apparatus, because the lenses of the writer which require the periodic cleaning are typically disposed in a rectangular arrangement, i.e., all the lenses can be cleaned at essentially the same time. However, there is a need for a simple and convenient way to clean such a lens array in situ, i.e., without requiring partial disassembly of the machine.
It is known to provide a removable replaceable sleeve member for an imaging cylinder or a blanket cylinder, as disclosed in the Chowdry, et al. patents (U.S. Pat. Nos. 6,456,816; 6,541,171; and 6,605,399), which are hereby incorporated by reference. A double-sleeved imaging cylinder or blanket cylinder is disclosed in the Chowdry, et al. patent (U.S. Pat. No. 6,377,772), which is hereby incorporated by reference.
The Shifley, et al. patents (U.S. Pat. Nos. 6,259,873; 6,263,177; and 6,484,002), which are hereby incorporated by reference, disclose a roller (such as a photoconductive roller or an intermediate transfer roller) which has a removable replaceable sleeve and a disconnectable supportive member which is disengaged and moved away from the roller so as to provide a free end for sleeve removal or replacement, the roller being supported in cantilevered fashion at the opposite end. With a new sleeve in place the supportive member is re-engaged to support the roller for operation. A mechanism can be provided for disconnecting/reconnecting supporting members from an imaging cylinder as well as from an associated blanket cylinder, thereby simultaneously leaving both cylinders supported in cantilever fashion, e.g., for sleeve replacement.
The Cormier, et al. patent (U.S. Pat. No. 6,394,943), which is hereby incorporated by reference, describes an image transfer drum inclusive of a mandrel having an air bearing to facilitate loading and removal of a resilient sleeve. The air bearing is provided with a pair of cooperating plates, one of which is scored with equally spaced and radially extending grooves. When urged together, the plates define a central air chamber and a plurality of radially extending passages serving to direct pressurized air radially from one end of the mandrel, at which end the sleeve can be removed and replaced. The pressurized air is conveyed to the central chamber via a pipe passing into the mandrel at the other end of the mandrel, at which other end the mandrel is supported in cantilever fashion during removal or replacement of a sleeve.
The Cormier, et al. provisional patent application (U.S. Provisional Patent Application Ser. No. 60/523,619), which is hereby incorporated by reference, discloses a double-sleeved roller inclusive of a mandrel similarly supported in cantilever fashion during replacement of a sleeve member. The mandrel provides an air bearing to facilitate removal or replacement of an outer sleeve. For replacement of an inner sleeve, a sleeve-replacement fixture is reversibly attached to the free end of the cantilevered mandrel. With the sleeve-replacement fixture attached, three air bearings are available to facilitate removal/mounting of the inner sleeve.
As is commonly known, contamination of certain critical surfaces of subsystem apparatus can result in reduced performance of an electrophotographic engine. Such contamination can include various types of particulates, e.g., toner dust, carrier dust, paper dust, hairs, and fibers. Moreover, aerosols such as fuser oil aerosols and the products of corona chemistry from corona chargers can contaminate surfaces. Despite a prevailing use of contamination control mechanisms, e.g., airflow systems, air conditioning systems, air purifying filters, and the like, the problem of lowered performance caused by contamination remains a fact of life in commercial electrophotographic machines, including modular electrophotographic color printing machines.
Thus, over a period of time of operation of a modular electrophotographic color printing machine employing, in the modules, LED writers having lens arrays, the lens surfaces of the lens arrays typically become contaminated, e.g., with particulate matter. The contamination reduces the amount of transmitted imaging light and thereby adversely affects image-wise exposure of corona-charged imaging cylinders. As a result, the lens surfaces typically require periodic cleaning. This can be a cumbersome process in a modular electrophotographic color-printing machine, where each LED writer is disposed close to the respective imaging cylinder. Typically, the LED writer is fixedly and precisely positioned with respect to the surface of the imaging cylinder, i.e., in practice the LED array is not retractable from the imaging cylinder. Were it in fact retractable, very little available space would typically be available for providing a suitable amount of retraction for a cleaning device to be inserted between imaging cylinder and lenses. Therefore, the imaging roller (which can be bulky and heavy) must be removed from the machine in order to clean the LED lenses. This is time consuming and also introduces a risk of damage to the roller, to the LED array, or to other subsystem elements.
The grids of gridded corona chargers can typically become contaminated by an accumulation of corona chemistry byproducts, which byproducts can desorb from the grids and cause blurring of images on the imaging cylinder. Or, the grids can be contaminated by particulate matter or by fibers, which can cause image defects as well as electrical arcing defects on an imaging cylinder surface. Thus each grid requires periodic cleaning, e.g., via wiping. While the inner surfaces of the grid can readily be cleaned by periodically wiping with a wiping mechanism internal to the corona charger, it is considerably more expensive to also clean the exterior surface of the grid by a mechanical device incorporated into the charger. In order to clean the exterior surface of a grid manually, e.g., by using a suitable cloth or a pad, the charger is typically removed from the machine.
Periodic cleaning of the corona wires of non-gridded corona chargers, sometimes used for the pre-clean charging function for imaging and blanket cylinders, can also be desirable. The low cost of such chargers can make it impractical to use a mechanical wiper integral with the charger. Non-gridded corona chargers are usually removed from the machine from time to time for manual cleaning of the corona wires.
Cleaning blades, which can be employed in cleaning stations, can become dirty after prolonged usage. As a result they require periodic cleaning, which typically necessitates removal of the blades from the machine. Other types of blade, such as for example doctor blades, scrapers, or skives, may similarly require periodic cleaning.
An erase lamp can be mounted prior to a cleaning station so as to illuminate an imaging cylinder for the purpose of regenerating the imaging cylinder between images, i.e., to remove ghost images. However, the erase lamp can accumulate exterior particulate or other contamination, thereby reducing the amount of transmitted light and thus compromising erase efficiency. Periodic cleaning of erase lamps is therefore usually necessary.
It is well known that iron carrier particles, which typically are a component of an electrophotographic developer, can be deposited on a photoconductor during toning of an electrostatic latent image via a magnetic brush. This type of deposition is sometimes referred to as “developer pickup” (DPU). It is known that in order to remove such iron particles from the photoconductor, a DPU scavenger device can be provided immediately after the toning station. The surface of the DPU scavenger device, which faces the photoconductor, requires periodic cleaning.
A sensor included in a densitometer for measuring toner lay-down can be located after the development or toning station and prior to the transfer station. Such a sensor can have a transparent protective surface that can gradually become dirty, e.g., by particulate contamination. For proper functioning of the densitometer, periodic cleaning of the transparent protective surface is typically required.
It will be evident that an electrophotographic machine is typically required to be partially disassembled for periodic cleanings of, for example, LED lens arrays, exterior surfaces of corona grids, corona wires, blades, sensors for densitometers, DPU scavengers, and erase lamps. These procedures can be cumbersome, time consuming, and therefore costly, especially for high speed modular printers where productivity is paramount.
It will be evident that there is a general need to provide in a (modular) electrophotographic engine a mechanism or apparatus to periodically clean, in situ, certain surfaces of subsystem components mounted around the periphery of a roller upon which a cleaning sleeve is mountable, e.g., to remove dust particles or other debris or contamination from these components. There is a particular need to be able to periodically clean the lens surfaces of a LED writer lens array such that the associated imaging roller remains supported in situ in the machine with the LED writer remaining unmoved from its operational position. Additionally, there can be a need to provide a mechanism or apparatus for easy periodic cleaning of other devices typically associated with an electrophotographic roller, such as erase lamps, sensors for densitometers, cleaning blades, doctor blades, DPU scavengers, charger grids included in gridded corona chargers, charger wires included in open-wire corona chargers, or rotatable members associated with the roller for operational use therewith. These needs can be met simply and cheaply by the subject invention.